1. Field of the Invention
This invention relates to fault location in electronic circuit, and more particularly to a method of isolating a fault to a single component, of a multiple component circuit and to a device for selectively isolating circuit portions of a plug-in electrical circuit module assembly.
2. Brief Description of the Prior Art
The integrated circuit and printed circuit board are responsible for much of miniaturization and manufacturing techniques employed in the electronics industry today. Test and service methods have been developed to speed testing of these devices. Such methods range from simple clip leads and "extender" printed circuit boards which facilitate clip lead and test probe attachment to intricate computer programs designed to "debug" entire printed circuit boards. Economically it is beyond the means of most electronics manufacturers to "debug" via a computer program. Yet the incentive to efficiently reduce test and calibration costs exists at all times.
Extenders such as found in U.S. Pat. Nos. 2,952,810 and 3,808,532 have come into demand because in the manufacture of electronic equipment, the necessity for compactness has resulted in the loss of adequate space within such equipment in which the proper testing of the components of the circuitry included therein can be accomplished. The advantages of testing circuits and components in their dynamic states and while being subjected toe very parametric value encountered in the usage of such equipment were sacrificed to the advantages of compactness. Optimum operational characteristics of such equipment are jeopardized by the lack of dynamic testing and accordingly the extenders are employed to render the suspected circuit readily and completely accessible for testing purposes while still being electrically connected to the basic equipment with full operational capabilities.
Similarly, in U.S. Pat. No. 3,147,054 the extenders are disclosed as having value in preventing inadvertent short circuits when testing closely packed components with a test probe.
It is thus seen that the basic approach has been substantially unchanged from the development of the extender for testing vacuum tubes as disclosed in U.S. Pat. No. 2,823,304, to the present time. It is noted that in the latter patent an extender is provided which, through the use of a rotatable switch, selectively makes contact with a vacuum tube pin or terminal and a voltmeter.
The purpose of fault testing can be to detect the presence of the fault and to determine the location of the fault. Conventionally, the test procedures and available devices contribute to the detection of faults but are lacking in their ability to localize a fault unless computer programs can be employed in the test procedure.